1. Field of the Invention
The present invention relates to compositions and methods for dermal administration of drugs, their method of making and method of use. In particular, the present invention is directed to a dermal drug delivery matrix system for the dermal application of one or more drugs, which includes a blend of two acrylic-based polymers having differing functionalities and a therapeutically effective amount of one or more drugs.
2. Description of Related Art
The use of a dermal drug delivery composition, for example a pressure-sensitive adhesive containing a medicament, namely, a drug, as a means for administering therapeutically effective amounts of the medicament is well known. Such known delivery compositions involve incorporation of a medicament into a carrier such as a polymeric and/or a pressure-sensitive adhesive formulation to form a composition of the medicament and a polymer or pressure-sensitive adhesive which also functions as a reservoir for the medicament. If the polymer is a pressure-sensitive adhesive, the pressures-sensitive adhesive also functions to adhere the composition directly to the skin without the requirement for any additional adhesives. The pressure-sensitive adhesive must adhere effectively to the skin and permit migration of the medicament from the carrier to the site of application and/or through the skin and into the bloodstream of the living organism.
Many factors influence the design and performance of dermal drug delivery devices, such as desired delivery rate, length of delivery, and the individual drugs themselves. These factors are described in detail in U.S. Pat. No. 5,474,783 (assigned to Noven Pharmaceuticals, Inc., the assignee of the present invention) which is hereby incorporated by reference in its entirety.
Dermal drug delivery compositions based on acrylic pressure-sensitive adhesive polymers are known in the dermal drug delivery art. These acrylic-based polymers are typically used as the pressure-sensitive adhesive by themselves as described in U.S. Pat. No. 4,390,520. They may also be used in combination with other polymers which may or may not be pressure-sensitive adhesive as described in U.S. Pat. No. 4,994,267 (assigned to the assignee of the present application Noven Pharmaceuticals, Inc.). In order to provide for adequate wear properties and drug delivery, acrylic-based pressure-sensitive adhesives are typically polymerized with functional monomers to provide functional groups on the acrylic-based adhesive.
By varying the amount of each type of monomer added, the adhesive and cohesive properties and drug solubility of the resulting polyacrylate can be changed as is known in the art. Typically, the polyacrylate is composed of at least 50% by weight of an acrylate or alkyl acrylate monomer, from 0% to 20% of a functional monomer copolymerizable with the acrylate, and from 0% to 40% of other monomers.
One drawback with the use of acrylic-based polymers with functional groups is that due to the generally high solubility of the drug in the polymer matrix, a large amount of drug generally must be incorporated into the dermal drug delivery composition to saturate it and provide an adequate flux to the skin of the user. Another drawback is that the functional groups provide reaction sites for undesirable degradation reactions of the drug with the polymer matrix.
One way of overcoming the problems of high drug loading and degradation is to physically blend the acrylic-based polymer with another polymer which has a different solubility parameter in order to adjust the solubility and flux of a drug in the blend. In other words, by selectively blending the polymers, a drug delivery system results which can incorporate low concentrations of drug and deliver the same at an adequate and controlled rate, or, alternatively, incorporate high concentrations of drugs while retaining good physical adhesive properties.
A blend of polymers which are particularly suitable are acrylic-based adhesives and polysiloxanes as described in U.S. Pat. No. 5,474,783. While these blends generally provide good results in terms of controlling the flux and the solubility of the drug within the matrix, polysiloxane adhesives are generally more expensive than acrylic-based adhesives resulting in higher production costs. Additionally, the usable range of solubility for silicone-containing blends is significantly lower than is sometimes desired.